Another online file editor (that I like much mre, personally) is
http://www.websitebakers.com/pages/admin/admin-tools/webbase-edit.phpBut what I normally do with working on templates is:
1. install a minimum version of the new template (just to keep filesize down), containing just an index.php and info.php
2. rename with FTP the new template folder on your server into something temporary
3. create with FTP a new template folder with the exact same
original name of the folder you renamed in step 2
4. FTP complete template files into the template folder manually created in step 3
5. delete the original (renamed) template folder though any online file editor, like the ones mentioned above.
Now you can keep using the template folder with FTP. Sometimes it may be needed to reload the template files into WB though the Admin>Addons>Advanced function if your changes don't work immediately, but most of the times WB just picks up your changes right after you have FTP'ed the changed file(s).